Diamonds are cut in many different shapes.
The first brilliant cut was introduced in the middle of the 17th century, which was known as the Single Cut and they had 8 facets at the top and 8 facets at the bottom with a table, totaling 17 facets.
As skills and technology advances, diamonds are then cut into various shapes which are decided by diamond cutters according to the shape of the rough diamond and the flaws within the diamond. A diamond cutter would also like to maximize its weight without compromising much on its brilliance. Most basic shapes are enhanced with trimmed or rounded corners, sometimes adding additional facets to the stone.
Nowadays specific cuts are made by companies using advanced laser cutting equipment and are licensed under their own brand names. The Hearts On Fire Diamond and the Asscher Cut are good examples.
The Round Brilliant Cut diamond is by far the most popular, because light entering the diamond can be optimized and reflected totally from within the stone to exit from the table and the crown facets, using precise mathematical calculations and advance optical theories of light waves based on the Refractive Index of diamond. A well cut RBC will have more flexibility in the balance of cut, color, clarity and weight and at the same time the fire and brilliance within the stone can be maintained.
The Princess Cut is the most popular of non-round diamond. It is also a favorite for couples as an engagement ring. Traditionally it is square in shape, though it may not be a perfect square. A length-to-width ratio of 1 to 1.05 would be the most perfect of a princess cut diamond.
The Emerald Cut diamond has a different pavilion from those of RBC and Princess Cut. Although its popularity is waning, an emerald cut diamond still maintains its charm as the old world elegance and nostalgia to it.
A new Cushion Cut is difficult to source and most of the present day Cushion Cut are only available at estate sales and auctions of old jewelry. The cushion cut is an antique cut that most often resembles a cross between the Old Mine Cut (a deep cut with large facets that was common in the late 19th and the early 20th centuries) and a modern oval cut. This cut is not as fiery or brilliant as many of the newer cuts, but it has a marvelously romantic and classic look and definitely stands out from the crowd of round brilliants.
Although the heart is the ultimate symbol of love, the Heart Diamond is not popular. There may be some customers who still prefer the old traditional symbol of a Heart Shape diamond but demand is still low.
The Pear Diamond is a beautiful and feminine with a round end on one side and a tapering point at the other end. Sometimes it is called a teardrop diamond, though most jewelers do not like this term. On an elongated pear shape diamond the length of the diamond creates a subtle slimming effect on the finger where it is worn. The pear shape diamond should have good symmetry to ensure that light is evenly distributed.
The Marquise Diamond is a traditional cut. The shape of a Marquise can maximize the carat weight, giving the viewer a much larger-looking diamond. The length of the Marquise also gives the appearance of long slender fingers of an Aristocrat. This is probably the fourth most popular shape behind the Round, Princess and Oval Shape.
The Oval Shape diamond is most similar to an RBC as it has beautiful brilliance and fire. The length of an Oval shape diamond can accentuate long slender fingers and it is quite a popular shape as the relatively symmetrical shape lends itself well to a variety of mounting styles.
The Radiant shape is a beautiful combination of the classic emerald cut and the sparkle of the round brilliant. The radiant cut is similar to the princess cut but usually has a more rectangular outline. Demand for Radiant shape is on the wane.
The Asscher Cut Diamond is a unique shape which is nearly identical to the emerald-cut, except that it is square. Asscher cut has a pavilion which is cut with rectangular facets in the same style as the emerald-cut. The Asscher cut, was pioneered by the Asscher brothers in Holland in 1902, is not a traditional choice but has gained deserved exposure recently because of celebrities wearing the cut.
References : http://www.dyjewels.com, http://www.amazon.com, http://www.princessplus.com, http://www.designchristianjewelry.com, http://www.hrdantwerp.be, http://www.belljewellers.com, http://www.addictedtodiamonds.com, http://1.bp.blogspot.com, http://www.madedesignerjewellery.com.au/, http://brittonjewelers.com, http://www.twinklediamonds.com.au, http://www.bluenile.com, http://engagementrings.lovetoknow.com, http://www.thediamondbuyingguide.com,